Module with transmit optical subassembly and receive optical subassembly

ABSTRACT

An optoelectronic module. In some embodiments, the module includes: a housing, a substantially planar subcarrier, a photonic integrated circuit, and an analog electronic integrated circuit. The subcarrier has a thermal conductivity greater than 10 W/m/K. The photonic integrated circuit and the analog electronic integrated circuit are secured to a first side of the subcarrier, and the subcarrier is secured to a first wall of the housing. A second side of the subcarrier, opposite the first side of the subcarrier, is parallel to, secured to, and in thermal contact with, an interior side of the first wall of the housing.

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is a continuation of U.S. patent applicationSer. No. 16/051,237, filed Jul. 31, 2018, entitled “MODULE WITH TRANSMITOPTICAL SUBASSEMBLY AND RECEIVE OPTICAL SUBASSEMBLY”, which claimspriority to and the benefit of U.S. Provisional Application No.62/539,929, filed Aug. 1, 2017, entitled “OPTOELECTRONIC PLUGGABLETRANSCEIVER MODULE WITH TRANSMIT OPTICAL SUBASSEMBLY AND RECEIVE OPTICALSUBASSEMBLY”, the entire contents of both of which are incorporatedherein by reference.

FIELD

One or more aspects of embodiments according to the present inventionrelate to optoelectronic modules.

BACKGROUND

Pluggable transceivers which include (i) one or more transmitters toconvert electrical signals carrying data to optical signals carrying thesame data and (ii) one or more receivers to convert optical signals toelectrical signals may be used, for example, in switching systems. Thedesign of a pluggable module may pose various challenges, includingrespecting space constraints, and keeping components in the modulewithin acceptable temperature ranges.

SUMMARY

According to an embodiment of the present disclosure there is provided atransceiver assembly, including: a housing; and an optical subassembly,the optical subassembly including: a fiber, a photonic integratedcircuit, an analog electronic integrated circuit, and a substantiallyplanar subcarrier; the subcarrier having a thermal conductivity greaterthan 10 W/m/K; the photonic integrated circuit and the analog electronicintegrated circuit being on the subcarrier; the fiber being coupled tothe photonic integrated circuit; the subcarrier being parallel to,secured to, and in thermal contact with, a first wall of the housing;the photonic integrated circuit being connected to the analog electronicintegrated circuit; and the optical subassembly having a plurality ofcontact pads for establishing electrical connections between the analogelectronic integrated circuit and test equipment probes, the opticalsubassembly being configured to be separately testable by supplyingpower to the optical subassembly through one or more of the contact padsand sending data to and and/or receiving data from the opticalsubassembly through one or more of the contact pads.

In one embodiment, the analog electronic integrated circuit is adjacentto the photonic integrated circuit and connected to the photonicintegrated circuit by a first plurality of wire bonds. In oneembodiment, the wire bonds extend from wire bond pads along an edge ofthe analog electronic integrated circuit to wire bond pads along anedge, of the photonic integrated circuit, nearest the analog electronicintegrated circuit.

In one embodiment, the optical subassembly further includes a flexibleprinted circuit, connected to the analog electronic integrated circuit.

In one embodiment, the optical subassembly further includes a routingboard, and the analog electronic integrated circuit is connected to theflexible printed circuit through the routing board.

In one embodiment, the routing board is a printed circuit including anorganic insulating material and conductive traces, the routing board isconnected to the analog electronic integrated circuit, along an edge ofthe analog electronic integrated circuit, by wire bonds.

In one embodiment, the flexible printed circuit is further connected tothe host board.

According to an embodiment of the present disclosure there is provided amodule, including: a housing; a substantially planar subcarrier; aphotonic integrated circuit; and an analog electronic integratedcircuit, the subcarrier having a thermal conductivity greater than 10W/m/K, the photonic integrated circuit and the analog electronicintegrated circuit being secured to a first side of the subcarrier, thesubcarrier being secured to a first wall of the housing, wherein asecond side of the subcarrier, opposite the first side of thesubcarrier, is parallel to, secured to, and in thermal contact with, aninterior side of the first wall of the housing.

In one embodiment, the photonic integrated circuit is adjacent to theanalog electronic integrated circuit.

In one embodiment, the photonic integrated circuit is connected to theanalog electronic integrated circuit by wire bonds.

In one embodiment, the wire bonds extend from wire bond pads along anedge of the analog electronic integrated circuit to wire bond pads alongan edge, of the photonic integrated circuit, nearest the analogelectronic integrated circuit.

In one embodiment, the module further includes an optical subassemblyincluding: the subcarrier; the photonic integrated circuit; and theanalog electronic integrated circuit, the optical subassembly having aplurality of contact pads for establishing electrical connectionsbetween the analog electronic integrated circuit and test equipmentprobes, the optical subassembly being configured to be separatelytestable by supplying power to the optical subassembly through one ormore of the contact pads and sending data to and and/or receiving datafrom the optical subassembly through one or more of the contact pads.

In one embodiment, the optical subassembly further includes a flexibleprinted circuit, connected to the analog electronic integrated circuit

In one embodiment, the optical subassembly further includes a routingboard connected to the analog electronic integrated circuit, along anedge of the analog electronic integrated circuit, by wire bonds; theanalog electronic integrated circuit is connected to the flexibleprinted circuit through the routing board; and the routing board is aprinted circuit including an organic insulating material and conductivetraces.

In one embodiment, the flexible printed circuit is connected to therouting board by solder.

In one embodiment, the module further includes a host board including amicrocontroller and/or a DC-DC converter, the host board being connectedto the routing board through the flexible printed circuit.

According to an embodiment of the present disclosure there is providedmethod for manufacturing a module, the method including: assembling anoptical subassembly including: a fiber, a photonic integrated circuit,an analog electronic integrated circuit, and a substantially planarsubcarrier, the photonic integrated circuit and the analog electronicintegrated circuit being on the subcarrier; testing the opticalsubassembly; determining that the testing of the optical subassembly wassuccessful; and in response to determining that the testing of thetesting the optical subassembly was successful, installing the opticalsubassembly in a housing, with the subcarrier being parallel to, securedto, and in thermal contact with, a first wall of the housing.

In one embodiment, the optical subassembly has a plurality of contactpads for establishing electrical connections between the analogelectronic integrated circuit and test equipment probes; and the testingof the optical subassembly includes: transmitting modulated light intothe photonic integrated circuit through the fiber, and verifying thepresence, at the contact pads, of electrical signals corresponding tothe modulation; or the testing of the optical subassembly includes:applying electrical signals to the contact pads, and verifying thepresence, in light transmitted through the fiber from the photonicintegrated circuit, of modulation corresponding to the electricalsignals.

In one embodiment, the method further includes: in response todetermining that the testing of the testing the optical subassembly wassuccessful, connecting a host board including a microcontroller and/or aDC-DC converter to the optical subassembly.

In one embodiment, the connecting of the host board to the opticalsubassembly includes soldering the host board to the opticalsubassembly.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features and advantages of the present disclosure willbe appreciated and understood with reference to the specification,claims, and appended drawings wherein:

FIG. 1A is a schematic cross-sectional view of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 1B is a schematic cross-sectional view of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 1C is a schematic cross-sectional view of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 1D is a schematic cross-sectional view of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 2 is a bottom view of a portion of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 3 is a bottom view of a portion of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 4 is an assembly sequence diagram, according to an embodiment ofthe present disclosure;

FIG. 5 is an assembly sequence diagram, according to an embodiment ofthe present disclosure;

FIG. 6 is an assembly sequence diagram, according to an embodiment ofthe present disclosure;

FIG. 7A is a view of a host board, according to an embodiment of thepresent disclosure;

FIG. 7B is a view of testable optical subassembly, according to anembodiment of the present disclosure;

FIG. 7C is a view of a portion of an optoelectronic module, according toan embodiment of the present disclosure;

FIG. 8A is a top view of a housing, according to an embodiment of thepresent disclosure;

FIG. 8B is a top view of a portion of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 9A is a top view of a portion of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 9B is a top view of an optoelectronic module, according to anembodiment of the present disclosure;

FIG. 10A is a top view of a portion of an optoelectronic module,according to an embodiment of the present disclosure;

FIG. 10B is a cross-sectional view, along section line 10B-10B of FIG.10A, of a portion of an optoelectronic module, according to anembodiment of the present disclosure;

FIG. 11A is a schematic cross-sectional view of an optoelectronicmodule, according to an embodiment of the present disclosure;

FIG. 11B is a schematic cross-sectional view of an optoelectronicmodule, according to an embodiment of the present disclosure;

FIG. 11C is a schematic cross-sectional view of an optoelectronicmodule, according to an embodiment of the present disclosure;

FIG. 12A is a schematic cross-sectional view of an optoelectronicmodule, according to an embodiment of the present disclosure;

FIG. 12B is a schematic top view of a portion of an optoelectronicmodule, according to an embodiment of the present disclosure; and

FIG. 12C is a cross-sectional view, along section line 12C-12C of FIG.12B, of an optoelectronic module, according to an embodiment of thepresent disclosure.

DETAILED DESCRIPTION

The detailed description set forth below in connection with the appendeddrawings is intended as a description of exemplary embodiments of amodule with transmit optical subassembly and receive optical subassemblyprovided in accordance with the present disclosure and is not intendedto represent the only forms in which the present disclosure may beconstructed or utilized. The description sets forth the features of thepresent disclosure in connection with the illustrated embodiments. It isto be understood, however, that the same or equivalent functions andstructures may be accomplished by different embodiments that are alsointended to be encompassed within the scope of the disclosure. Asdenoted elsewhere herein, like element numbers are intended to indicatelike elements or features.

FIGS. 1A-1D show schematic cross-sectional views of several embodimentseach including a transceiver in a quad small form-factor pluggable(QSFP) package. Referring to FIGS. 1A and 1B, in some embodiments anoptical fiber 105 connects a photonic integrated circuit (PIC) 110 to aMulti-fiber Push On (MPO) connector 115. The PIC 110 is connected by oneor more wire bonds 120 to an analog electronic integrated circuit, e.g.,an analog application specific integrated circuit (aASIC) 125, which isconnected by one or more wire bonds 120 to a routing board 130, whichmay be a printed circuit board on an organic substrate (e.g., a polymeror fiberglass-reinforced polymer substrate). The PIC 110 may be one of aplurality of PICs 110 (e.g., the module may include both a transmitterPIC and a receiver PIC), and the aASIC 125 may be one of a plurality ofaASICs 125 (there being, for example, one aASIC 125 for each PIC 110).The aASIC 125 and the PIC may be bare die. For example, the aASIC 125may be a bare silicon die, and the PIC 110 may be a bare silicon die(which, in the case of a transmitter PIC, may include a bare laser die(e.g., a bare die of another semiconductor, different from silicon)mounted on a bare silicon die (as discussed in further detail below)).The routing board 130 may be fabricated using a process capable offorming fine pitch features, e.g., traces and wire bond pads on a pitchof 100 microns. The PIC 110, aASIC 125, and routing board 130 may besecured to (e.g., bonded to), and supported by, a subcarrier 135, whichmay be a block, or a block with a stepped thickness as shown, formed ofa thermally conductive material (e.g., a material having a thermalconductivity exceeding 10 W/m/K), e.g., copper. The subcarrier may besubstantially planar, i.e., it may have the shape of a sheet havingdifferent thicknesses in different regions of the sheet, e.g., having agreater thickness in the region to which the aASIC 125 is secured thanin the region to which the PIC 110 and a TEC 140 (discussed in furtherdetail below) are secured. That is, in one or more embodiments, thesubcarrier 135 may be a single, monolithic, substantially planarsubcarrier. In a system using a QSFP package, thermal control of the toppackage wall 137 may be provided (e.g., the system may be designed—e.g.,with a heat sink—to ensure that the temperature of the top package wallnot exceed a specified value). As such, in the embodiments of FIGS. 1Aand 1B, heat may be conducted out of the package through the subcarrier135 and through the top package wall 137.

The PIC 110 may be secured to a thermoelectric cooler (TEC) 140 whichmay be secured to the subcarrier 135, as shown. In some embodiments, ahost board 145, which may be an organic printed circuit board, hasinstalled on it a microcontroller 150 and a DC-DC converter 155, and ithas a card-edge connector 160 at the electrical end of the QSFP package.The routing board may be connected to the host board by a flexiblecircuit or “flex circuit” 165 (FIG. 1A) or by a low profile connectorarray 170 (or “socket”) (e.g., a Z-RAY™ ultra-low profile arrayavailable from Samtec (samtec.com)) (FIG. 1B). Because the conductorsmay spread out on the routing board 130 and/or on the flex circuit 165,the host board is, in some embodiments, fabricated using a lower-costprocess not capable of forming fine pitch features. A similarconfiguration may be used regardless of whether the PIC 110 and theaASIC 125 form a transmitter (transmitting light through the fiber) or areceiver (receiving light through the fiber). In the case of atransmitter, the PIC may include a modulator, and a laser (e.g., aseparate laser chip) may be mounted on the PIC, and optically coupled toit, and the aASIC may include a drive circuit for the modulator. In thecase of a receiver, the PIC may include a photodetector, and the aASICmay include a transimpedance amplifier to amplify the signal from thephotodetector. Each PIC 110 may include an array of modulators orphotodetectors, and each aASIC 125 may include a corresponding array ofdrive circuits or transimpedance amplifiers.

Each PIC 110 may include a waveguide having transverse dimensions ofapproximately 10 microns at a point at which light couples into thewaveguide from the fiber 105, or from the fiber 105 into the waveguide.A mode adapter, e.g., a taper, may guide the light and transform theoptical mode to one that propagates in a waveguide having transversedimensions of approximately 3 microns. The 3 micron waveguide may beused to guide the light to a photodetector, or from a modulator. Furthermode adapters (e.g., at a modulator) may be used to effect furtherchanges in the size or shape of the optical mode, e.g., to enable lightto propagate through a modulator fabricated on a waveguide with smallertransverse dimension (for improved modulator performance). In someembodiments similar to that of FIG. 1A, the routing board 130 is omittedand the aASIC 125 is connected directly to the flex circuit 165, whichis bonded directly to the subcarrier 135. In such an embodiment, longerwire bonds may be used to accommodate the difference in height betweenthe surface of the aASIC 125 and the surface of the flex circuit (whichmay be significantly thinner than the aASIC 125), or the difference inheight may be reduced by thinning the aASIC die, or by using asubcarrier 135 with a stepped thickness (i.e., a subcarrier 135 having agreater thickness under the flex circuit 165 than under the aASIC 125).The flex circuit 165 may be a printed circuit composed of one or morelayers of conductive traces and one or more flexible insulating layers.The flexible insulating layers may be composed of a film of plastic(e.g., a film of polyimide) capable of withstanding solderingtemperatures, and the flex circuit 165 may be connected to the routingboard 130 and to the host board 145 by soldering.

In some embodiments the TEC 140 is absent and the PIC 110 is bondeddirectly to the subcarrier, or is bonded to an insulating layer bondedto the subcarrier. In some embodiments, a heater is secured to orintegrated into the PIC 110 and the temperature of the PIC 110 isactively controlled, based on a signal from a temperature sensor on orintegrated into the PIC 110. In such an embodiment, the insulating layermay enable the heater to raise the temperature of the PIC 110 withoutconsuming an excessive amount of power.

FIG. 1C shows an embodiment in which the MPO connector 115 is absent andthe fiber 105 extends directly from the PIC 110 to the exterior of thepackage. Such a configuration may be referred to as an active opticalcable (AOC) configuration. FIG. 1D shows a related embodiment in whichthe PIC 110 is more distant from the front end (or “optical end”) of thepackage, facilitating the inclusion of an MPO connector 115. In FIGS. 1Cand 1D, the PIC 110 and the aASIC 125 may be bonded to a substrate 175,which may be a printed circuit board including one or more layerscontaining conductive traces and one or more organic insulating layers(e.g., polymer or fiberglass-reinforced polymer insulating layers), withthermal vias 180 for forming a thermal path between (i) the PIC 110 andthe aASIC 125 and (ii) a thermal block 185 which supports the substrate175 and provides a thermal path between the substrate and the bottomwall (or “lower wall”) 187 of the package enclosure. In some systemsusing QSFP packages the lower wall 187 of the package is not directlyconnected to the heat sink; accordingly, in the embodiments of FIGS. 1Cand 1D the side walls of the package may be used to conduct heat to thetop package wall. Wire bonds 120 may be used to connect the PIC 110 tothe aASIC 125 and to connect the aASIC 125 to the substrate 175. Thesubstrate 175 may be fabricated using a process capable of forming finepitch features, e.g., traces and wire bond pads on a pitch of 100microns.

A dual flex circuit (i.e., two parallel flex circuits 165), is used inthe embodiment of FIG. 1C to connect the substrate 175 to a host board145 which has a card-edge connector 160 at the electrical end of theQSFP package, and which has installed on it a microcontroller 150 and aDC-DC converter 155. In the embodiment of FIG. 1D the card-edgeconnector 160 at the electrical end of the QSFP package is on thesubstrate 175, and a separate host board 145 has installed on it amicrocontroller 150 and a DC-DC converter 155 and is connected to thesubstrate 175 by a flex circuit 165.

FIG. 2 shows a bottom view of the embodiment of FIGS. 1A and 1B, in oneembodiment, and FIG. 3 shows a bottom view of the embodiment of FIGS. 1Aand 1B, in another embodiment. The routing board extends around theaASICs 125 and the PICs 110 so that wire bonds (not shown), fordelivering power or control signals to these components (or forproviding laser drive current to the laser on the transmitter PIC) maybe formed along the side edges of these components. The host board 145and flex circuit 165 are not shown in FIGS. 2 and 3. Wire bonds for dataconnections (shown in FIGS. 1A and 1B, and, for the data connectionsbetween the aASICs and the PICs, in FIGS. 2 and 3) may be present alongthe end edges of the aASICs and the PICs.

FIGS. 4-9 show an assembly sequence for the embodiment of FIGS. 1A and1B. Referring to FIG. 4, each fiber 105 (of the fibers of a fiber ribbon405, the other end of which is terminated in an MPO connector 115 (FIG.7B; not shown in FIGS. 4-6) is aligned in a respective V-groove (e.g.,of an array of V-grooves) on the PIC 110 and secured in place to form a“PICtail” 410. The PICtails 410 are secured to the subcarrier (or“carrier”) 135 along with the aASICs 125, either directly, to form afirst subassembly 415, or (in the alternate sequence shown by dashedarrows) the PICs 110 may be bonded to a TEC 140 which may be bonded tothe subcarrier 135. Referring to FIG. 5, a rigid-flex circuit 505 (thecombination of the routing board 130 and the flex-circuit 165, which maybe separately assembled) is then bonded to the first subassembly 415 ofFIG. 4 to form a testable transmit-receive optical subassembly (TROSA)510 (including the fiber-coupled PICs 110 and the aASICs 125), with pads515 suitable for making contact with test equipment probes, that mayprovide power to the TROSA and send or receive data through it. Thetestable TROSA 510 thus makes it possible to identify and discard adefective optical subassembly without discarding with it, e.g., a hostboard having installed on it a microcontroller and a DC-DC converter.

Referring to FIG. 6, a cover 610 may then be secured to the TROSA (e.g.,to protect it during further handling before the package is assembled).The TROSA 510 may be tested (by supplying modulated light to thereceivers and verifying that suitable corresponding electrical signalsare produced at the pads 515, and by supplying electrical signals to thepads 515, and verifying that suitably modulated light is produced by thetransmitters) either before or after installation of the cover 610. Ifthe test is successful, assembly of the module may proceed; if it isunsuccessful, the TROSA 510 may be discarded or reworked.

Referring to FIGS. 7A-7C, the flex circuit of the TROSA 510 is thensoldered to the host board 145. FIG. 7C shows the TROSA 510 soldered tothe host board 145, with the subcarrier 135 facing up and the cover 610facing the host board 145. Semicircular cutouts 710 (not shown in thepreceding drawings) may be used to register the TROSA 510 and the hostboard 145 to the module housing.

The resulting subassembly may then be installed in a QSFP packagehousing. FIG. 8A shows the cast housing 805 with registration features810 for engaging the semicircular cutouts 710 of the TROSA 510 and ofthe host board 145. FIG. 8B shows the TROSA 510 and the host board 145installed in the housing 805. A thermal pad 905 may be placed on thesubcarrier (FIG. 9A) and a lid may be installed on the QSFP packagehousing, to complete the assembly (FIG. 9B). FIG. 10A shows a top viewof the assembly with the lid removed and FIG. 10B shows across-sectional view, along section line 10B-10B of FIG. 10A, of theassembly.

FIGS. 11A-11C show embodiments in which the PIC 110 and the aASIC 125are secured, directly or indirectly, to a subcarrier to form a testableTROSA including the fiber 105, the MPO connector 115, the PIC 110, theaASIC 125, the TEC 140 (if present), and the subcarrier 135. Aftertesting, the TROSA is installed into a cutout in the host board 145 andthe aASIC 125 is wire bonded to the host board 145. In FIGS. 11A-11C,the module is shown in an orientation in which the wall of the module towhich a heat sink is directly connected, in operation, is the lowerwall. In the embodiment of FIG. 11C, a printed circuit board withthermal vias 1110 supports the PIC 110 and the aASIC 125 and is in turnsupported by the subcarrier 135. Wire bonds from the PIC 110 to theprinted circuit board with thermal vias 1110 and from the host board 145to the printed circuit board with thermal vias 1110 provide (along withtraces on the printed circuit board with thermal vias 1110) low speedconnections such as power and control connections. In the embodiments ofFIGS. 11A and 11B, testing may be accomplished by probing pads on theaASIC 125. In the embodiment of FIG. 11C, pads on the printed circuitboard with thermal vias 1110 may instead be probed; this may facilitatetesting, as the pads on the substrate may be larger and may have acoarser pitch than pads on the aASIC aASIC in the embodiments of FIGS.11A and 11B. In the embodiment of FIG. 11C, a pedestal 1115 (e.g., acast pedestal that is an integral part of the module housing) supportsthe thermal pad 905 which supports the subcarrier 135.

FIGS. 12A-12C show another embodiment of a transceiver module. In thisembodiment a coined, “top-drop” subcarrier 135 (which may be a coppersubcarrier) supports the PICs 110 and the aASICs 125 as shown. After theTROSA is tested, the subcarrier 135 is installed in (e.g., “droppedinto”) a cutout (e.g., a rectangular cutout) in the host board 145 andthe aASIC 125 is connected to the host board 145 by wire bonds. Anelectrical routing board 1210 is connected to the host board 145, to thePICs 110 and to the aASICs 125 by wire bonds, and provides low speedconnections to the PICs 110 and to the aASICs 125.

Although exemplary embodiments of a module with transmit opticalsubassembly and receive optical subassembly have been specificallydescribed and illustrated herein, many modifications and variations willbe apparent to those skilled in the art. Accordingly, it is to beunderstood that a module with transmit optical subassembly and receiveoptical subassembly constructed according to principles of thisdisclosure may be embodied other than as specifically described herein.The invention is also defined in the following claims, and equivalentsthereof.

What is claimed is:
 1. A transceiver assembly, comprising: a housing; anoptical subassembly; and a host board comprising a printed circuitboard, the optical subassembly comprising: a fiber, a photonicintegrated circuit, an analog electronic integrated circuit, and asingle, monolithic, substantially planar subcarrier; and athermoelectric cooler; the subcarrier having a thermal conductivitygreater than 10 W/m/K; the photonic integrated circuit and the analogelectronic integrated circuit being on the subcarrier; thethermoelectric cooler being between the subcarrier and only the photonicintegrated circuit among the photonic integrated circuit and the analogelectronic integrated circuit; the fiber being coupled to the photonicintegrated circuit; the subcarrier being parallel to, secured to, and inthermal contact with, a first wall of the housing; the photonicintegrated circuit being connected to the analog electronic integratedcircuit; and the optical subassembly having a plurality of contact padsfor establishing electrical connections between the analog electronicintegrated circuit and test equipment probes, the optical subassemblybeing configured to be separately testable by supplying power to theoptical subassembly through one or more of the contact pads and sendingdata to and/or receiving data from the optical subassembly through oneor more of the contact pads.
 2. The transceiver assembly of claim 1,wherein the analog electronic integrated circuit is adjacent to thephotonic integrated circuit and connected to the photonic integratedcircuit by a first plurality of wire bonds.
 3. The transceiver assemblyof claim 2, wherein the wire bonds extend from wire bond pads along anedge of the analog electronic integrated circuit to wire bond pads alongan edge, of the photonic integrated circuit, nearest the analogelectronic integrated circuit.
 4. The transceiver assembly of claim 3,further comprising a flexible printed circuit, connected to the analogelectronic integrated circuit.
 5. The transceiver assembly of claim 4,wherein: the optical subassembly further comprises a routing board, andthe analog electronic integrated circuit is connected to the flexibleprinted circuit through the routing board.
 6. The transceiver assemblyof claim 5, wherein: the routing board is a printed circuit comprisingan organic insulating material and conductive traces, the routing boardis connected to the analog electronic integrated circuit, along an edgeof the analog electronic integrated circuit, by wire bonds.
 7. Thetransceiver assembly of claim 6, wherein the flexible printed circuit isfurther connected to the host board.
 8. The transceiver assembly ofclaim 1, wherein a thickness of a region of the subcarrier on which theanalog electronic integrated circuit is located is greater than athickness of a region of the subcarrier on which the photonic integratedcircuit and the thermoelectric cooler are located.
 9. A module,comprising: a housing; a substantially planar subcarrier; a photonicintegrated circuit; and an analog electronic integrated circuit, thesubcarrier having a thermal conductivity greater than 10 W/m/K, thephotonic integrated circuit and the analog electronic integrated circuitbeing secured to a first side of the subcarrier, the subcarrier beingsecured to a first wall of the housing, wherein a second side of thesubcarrier, opposite the first side of the subcarrier, is parallel to,secured to, and in thermal contact with, an interior side of the firstwall of the housing.
 10. The module of claim 9, wherein the photonicintegrated circuit is adjacent to the analog electronic integratedcircuit.
 11. The module of claim 10, wherein: the photonic integratedcircuit is connected to the analog electronic integrated circuit by wirebonds, and the wire bonds extend from wire bond pads along an edge ofthe analog electronic integrated circuit to wire bond pads along anedge, of the photonic integrated circuit, nearest the analog electronicintegrated circuit.
 12. The module of claim 11, further comprising anoptical subassembly comprising: the subcarrier; the photonic integratedcircuit; and the analog electronic integrated circuit, the opticalsubassembly having a plurality of contact pads for establishingelectrical connections between the analog electronic integrated circuitand test equipment probes, the optical subassembly being configured tobe separately testable by supplying power to the optical subassemblythrough one or more of the contact pads and sending data to and and/orreceiving data from the optical subassembly through one or more of thecontact pads.
 13. The module of claim 12, wherein the opticalsubassembly further comprises a flexible printed circuit, connected tothe analog electronic integrated circuit.
 14. The module of claim 13,wherein: the optical subassembly further comprises a routing boardconnected to the analog electronic integrated circuit, along an edge ofthe analog electronic integrated circuit, by wire bonds; the analogelectronic integrated circuit is connected to the flexible printedcircuit through the routing board; and the routing board is a printedcircuit comprising an organic insulating material and conductive traces.15. The module of claim 14, wherein the flexible printed circuit isconnected to the routing board by solder.
 16. The module of claim 15,further comprising a host board comprising a microcontroller and/or aDC-DC converter, the host board being connected to the routing boardthrough the flexible printed circuit.
 17. A method for manufacturing amodule, the method comprising: assembling an optical subassemblycomprising: a fiber, a photonic integrated circuit, an analog electronicintegrated circuit, a single, monolithic substantially planarsubcarrier, and a thermoelectric cooler, the photonic integrated circuitand the analog electronic integrated circuit being on the subcarrier,the thermoelectric cooler being between the subcarrier and only thephotonic integrated circuit among the photonic integrated circuit andthe analog electronic integrated circuit; testing the opticalsubassembly; determining that the testing of the optical subassembly wassuccessful; and in response to determining that the testing of theoptical subassembly was successful: installing, in a housing: theoptical subassembly, and a host board comprising a printed circuitboard, with: the subcarrier being parallel to, secured to, and inthermal contact with, a first wall of the housing.
 18. The method ofclaim 17, wherein: the optical subassembly has a plurality of contactpads for establishing electrical connections between the analogelectronic integrated circuit and test equipment probes; and the testingof the optical subassembly comprises: transmitting modulated light intothe photonic integrated circuit through the fiber, and verifying thepresence, at the contact pads, of electrical signals corresponding tothe modulation of the modulated light; or the testing of the opticalsubassembly comprises: applying electrical signals to the contact pads,and verifying the presence, in light transmitted through the fiber fromthe photonic integrated circuit, of modulation corresponding to theelectrical signals.
 19. The method of claim 18, further comprising: inresponse to determining that the testing of the optical subassembly wassuccessful, connecting the host board to the optical subassembly,wherein the host board comprises a microcontroller and/or a DC-DCconverter.
 20. The method of claim 19, wherein the connecting of thehost board to the optical subassembly comprises soldering the host boardto the optical subassembly.